The prime objective of this project is the understanding of neuronal mechanisms underlying visual perception; such an understanding is necessary in order to study the alterations in functions that disturb or abolish vision in various disease states. One of the keys to understanding of the connections between neurons, and the genetic determinants of those connections. A very promising tool for unraveling the determinants of interneuronal connections is the study of genetic mutations that affect the nervous system directly. The mouse, Mus musculus, is the mammalian species most suitable for the study of mutations affecting the nervous system. This project will concentrate on an autosomal recessive mutation in mouse called reeler that is associated with a specific disturbance in the cytoarchitecture of the cortex of telencephalon and cerebellum; very few non-cortical structures are involved. The mutation disrupts events controlling cell intractions at the time when relative positions are achieved within the cortex, resulting in a characteristic abnormality in cortical layers. The visual system of normal and reeler mice will be studied by the techniques of microelectrode recording with receptive field mapping, and by the techniques of experimental neuroanatomy. With these techniques it will be possible to determine whether the input to the visual cortex is normal in reeler, and then how the functional organization of the mutant visual cortex differs from normal. An elucidation of the defect in reeler should provide information on how the neuronal circuity of the visual cortex is derived.